Since a π-conjugated compound with a fluoroalkyl group introduced thereinto has increased electron acceptability, the compound is expected to be developed as an electron-transport material such as an n-type organic semiconductor. From this viewpoint, recently, there has been increased research into compounds with a fluoroalkyl group introduced into a thiophene ring, particularly oligothiophene (for example, Patent Documents 1 to 4). These compounds can be produced, for example, by a coupling reaction between bromothiophene and fluoroalkyl bromide or fluoroalkyl iodide in the presence of a stoichiometric amount of copper. However, the positions wherein a fluoroalkyl group can be introduced without impairing the effective conjugation of oligothiophene are limited.
On the other hand, it was proved that oligomer containing, as a base unit, thiophene having a cyclopentane ring condensed therewith had an increased effective conjugation length as compared to oligothiophene having a linear alkyl group (Non-Patent Document 1).
From the viewpoint described above, the condensed ring structure formed of a hexafluorocyclopentane ring and an aromatic ring, particularly, for example, a thiophene ring, is attracting attention. For example, a compound including a 3,3,4,4,5,5-hexafluorocyclopenta[c]thiophene structure is expected to be produced in view of, for example, improving the solubility in an organic solvent and maintaining the 7-conjugation planarity as well as lowering the LUMO level through introduction of a fluorocyclopentane ring. However, it was not possible to produce such a compound by the conventional technology.    Non-Patent Document 1: Izumi, T.; Kobashi, S.; Takimiya, K.; Aso, Y; Otsubo, T. J. Am. Chem. Soc. 2003, 125, 5286.    Patent Document 1: U.S. Patent Application Publication No. 2004/186266    Patent Document 2: U.S. Patent Application Publication No. 2004/183068    Patent Document 3: International Publication No. WO 2003/010778    Patent Document 4: European Patent Application Publication No. 1279689